1 /* $NetBSD: ipsec_input.c,v 1.81 2024/07/05 04:31:54 rin Exp $ */
2 /* $FreeBSD: ipsec_input.c,v 1.2.4.2 2003/03/28 20:32:53 sam Exp $ */
3 /* $OpenBSD: ipsec_input.c,v 1.63 2003/02/20 18:35:43 deraadt Exp $ */
4
5 /*
6 * The authors of this code are John Ioannidis (ji@tla.org),
7 * Angelos D. Keromytis (kermit@csd.uch.gr) and
8 * Niels Provos (provos@physnet.uni-hamburg.de).
9 *
10 * This code was written by John Ioannidis for BSD/OS in Athens, Greece,
11 * in November 1995.
12 *
13 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
14 * by Angelos D. Keromytis.
15 *
16 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
17 * and Niels Provos.
18 *
19 * Additional features in 1999 by Angelos D. Keromytis.
20 *
21 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
22 * Angelos D. Keromytis and Niels Provos.
23 * Copyright (c) 2001, Angelos D. Keromytis.
24 *
25 * Permission to use, copy, and modify this software with or without fee
26 * is hereby granted, provided that this entire notice is included in
27 * all copies of any software which is or includes a copy or
28 * modification of this software.
29 * You may use this code under the GNU public license if you so wish. Please
30 * contribute changes back to the authors under this freer than GPL license
31 * so that we may further the use of strong encryption without limitations to
32 * all.
33 *
34 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
35 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
36 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
37 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
38 * PURPOSE.
39 */
40
41 #include <sys/cdefs.h>
42 __KERNEL_RCSID(0, "$NetBSD: ipsec_input.c,v 1.81 2024/07/05 04:31:54 rin Exp $");
43
44 /*
45 * IPsec input processing.
46 */
47
48 #if defined(_KERNEL_OPT)
49 #include "opt_inet.h"
50 #endif
51
52 #include <sys/param.h>
53 #include <sys/systm.h>
54 #include <sys/mbuf.h>
55 #include <sys/domain.h>
56 #include <sys/protosw.h>
57 #include <sys/socket.h>
58 #include <sys/errno.h>
59 #include <sys/syslog.h>
60
61 #include <net/if.h>
62 #include <net/route.h>
63
64 #include <netinet/in.h>
65 #include <netinet/in_systm.h>
66 #include <netinet/ip.h>
67 #include <netinet/ip_var.h>
68 #include <netinet/in_var.h>
69 #include <netinet/in_proto.h>
70 #include <netinet/udp.h>
71 #include <netinet/tcp.h>
72
73 #include <netinet/ip6.h>
74 #ifdef INET6
75 #include <netinet6/in6.h>
76 #include <netinet6/ip6_var.h>
77 #include <netinet6/ip6_private.h>
78 #include <netinet6/scope6_var.h>
79 #endif
80 #include <netinet/in_pcb.h>
81
82 #include <netipsec/ipsec.h>
83 #include <netipsec/ipsec_private.h>
84 #ifdef INET6
85 #include <netipsec/ipsec6.h>
86 #endif
87 #include <netipsec/ah_var.h>
88 #include <netipsec/esp.h>
89 #include <netipsec/esp_var.h>
90 #include <netipsec/ipcomp_var.h>
91
92 #include <netipsec/key.h>
93 #include <netipsec/keydb.h>
94
95 #include <netipsec/xform.h>
96 #include <netinet6/ip6protosw.h>
97
98 #define IPSEC_ISTAT(p, x, y, z) \
99 do { \
100 switch (p) { \
101 case IPPROTO_ESP: \
102 ESP_STATINC(x); \
103 break; \
104 case IPPROTO_AH: \
105 AH_STATINC(y); \
106 break; \
107 default: \
108 IPCOMP_STATINC(z); \
109 break; \
110 } \
111 } while (/*CONSTCOND*/0)
112
113 /*
114 * fixup TCP/UDP checksum
115 *
116 * XXX: if we have NAT-OA payload from IKE server,
117 * we must do the differential update of checksum.
118 *
119 * XXX: NAT-OAi/NAT-OAr derived from IKE initiator/responder.
120 * how to know the IKE side from kernel?
121 */
122 static struct mbuf *
ipsec4_fixup_checksum(struct mbuf * m)123 ipsec4_fixup_checksum(struct mbuf *m)
124 {
125 struct ip *ip;
126 struct tcphdr *th;
127 struct udphdr *uh;
128 int poff, off;
129 int plen;
130
131 if (m->m_len < sizeof(*ip)) {
132 m = m_pullup(m, sizeof(*ip));
133 if (m == NULL)
134 return NULL;
135 }
136 ip = mtod(m, struct ip *);
137 poff = ip->ip_hl << 2;
138 plen = ntohs(ip->ip_len) - poff;
139
140 switch (ip->ip_p) {
141 case IPPROTO_TCP:
142 M_REGION_GET(th, struct tcphdr *, m, poff, sizeof(*th));
143 if (th == NULL)
144 return NULL;
145 off = th->th_off << 2;
146 if (off < sizeof(*th) || off > plen) {
147 m_freem(m);
148 return NULL;
149 }
150 th->th_sum = 0;
151 th->th_sum = in4_cksum(m, IPPROTO_TCP, poff, plen);
152 break;
153 case IPPROTO_UDP:
154 M_REGION_GET(uh, struct udphdr *, m, poff, sizeof(*uh));
155 if (uh == NULL)
156 return NULL;
157 off = sizeof(*uh);
158 if (off > plen) {
159 m_freem(m);
160 return NULL;
161 }
162 uh->uh_sum = 0;
163 uh->uh_sum = in4_cksum(m, IPPROTO_UDP, poff, plen);
164 break;
165 default:
166 /* no checksum */
167 return m;
168 }
169
170 return m;
171 }
172
173 static void
nat_t_ports_get(struct mbuf * m,uint16_t * dport,uint16_t * sport)174 nat_t_ports_get(struct mbuf *m, uint16_t *dport, uint16_t *sport)
175 {
176 struct m_tag *tag;
177
178 if ((tag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS))) {
179 *sport = ((uint16_t *)(tag + 1))[0];
180 *dport = ((uint16_t *)(tag + 1))[1];
181 } else
182 *sport = *dport = 0;
183 }
184
185 static uint32_t
spi_get(struct mbuf * m,int sproto,int skip)186 spi_get(struct mbuf *m, int sproto, int skip)
187 {
188 uint32_t spi;
189 uint16_t cpi;
190
191 switch (sproto) {
192 case IPPROTO_ESP:
193 m_copydata(m, skip, sizeof(spi), &spi);
194 return spi;
195 case IPPROTO_AH:
196 m_copydata(m, skip + sizeof(spi), sizeof(spi), &spi);
197 return spi;
198 case IPPROTO_IPCOMP:
199 m_copydata(m, skip + sizeof(cpi), sizeof(cpi), &cpi);
200 return htonl(ntohs(cpi));
201 default:
202 panic("%s called with bad protocol number: %d\n", __func__,
203 sproto);
204 }
205 }
206
207
208 /*
209 * ipsec_common_input gets called when an IPsec-protected packet
210 * is received by IPv4 or IPv6. Its job is to find the right SA
211 * and call the appropriate transform. The transform callback
212 * takes care of further processing (like ingress filtering).
213 */
214 static int
ipsec_common_input(struct mbuf * m,int skip,int protoff,int af,int sproto)215 ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto)
216 {
217 char buf[IPSEC_ADDRSTRLEN], buf2[IPSEC_ADDRSTRLEN];
218 union sockaddr_union src_address, dst_address;
219 struct secasvar *sav;
220 u_int32_t spi;
221 u_int16_t sport;
222 u_int16_t dport;
223 int error;
224
225 IPSEC_ISTAT(sproto, ESP_STAT_INPUT, AH_STAT_INPUT,
226 IPCOMP_STAT_INPUT);
227
228 KASSERT(m != NULL);
229
230 if ((sproto == IPPROTO_ESP && !esp_enable) ||
231 (sproto == IPPROTO_AH && !ah_enable) ||
232 (sproto == IPPROTO_IPCOMP && !ipcomp_enable)) {
233 m_freem(m);
234 IPSEC_ISTAT(sproto, ESP_STAT_PDROPS, AH_STAT_PDROPS,
235 IPCOMP_STAT_PDROPS);
236 return EOPNOTSUPP;
237 }
238
239 if (m->m_pkthdr.len - skip < 2 * sizeof(u_int32_t)) {
240 m_freem(m);
241 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
242 IPCOMP_STAT_HDROPS);
243 IPSECLOG(LOG_DEBUG, "packet too small\n");
244 return EINVAL;
245 }
246
247 /* Retrieve the SPI from the relevant IPsec header */
248 spi = spi_get(m, sproto, skip);
249
250 /* find the source port for NAT-T */
251 nat_t_ports_get(m, &dport, &sport);
252
253 /*
254 * Find the SA and (indirectly) call the appropriate
255 * kernel crypto routine. The resulting mbuf chain is a valid
256 * IP packet ready to go through input processing.
257 */
258 memset(&src_address, 0, sizeof (src_address));
259 memset(&dst_address, 0, sizeof(dst_address));
260 src_address.sa.sa_family = af;
261 dst_address.sa.sa_family = af;
262 switch (af) {
263 #ifdef INET
264 case AF_INET:
265 src_address.sin.sin_len = sizeof(struct sockaddr_in);
266 dst_address.sin.sin_len = sizeof(struct sockaddr_in);
267 m_copydata(m, offsetof(struct ip, ip_src),
268 sizeof(struct in_addr),
269 &src_address.sin.sin_addr);
270 m_copydata(m, offsetof(struct ip, ip_dst),
271 sizeof(struct in_addr),
272 &dst_address.sin.sin_addr);
273 break;
274 #endif
275 #ifdef INET6
276 case AF_INET6:
277 src_address.sin6.sin6_len = sizeof(struct sockaddr_in6);
278 dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6);
279 m_copydata(m, offsetof(struct ip6_hdr, ip6_src),
280 sizeof(struct in6_addr),
281 &src_address.sin6.sin6_addr);
282 m_copydata(m, offsetof(struct ip6_hdr, ip6_dst),
283 sizeof(struct in6_addr),
284 &dst_address.sin6.sin6_addr);
285 if (sa6_recoverscope(&dst_address.sin6)) {
286 m_freem(m);
287 return EINVAL;
288 }
289 break;
290 #endif
291 default:
292 IPSECLOG(LOG_DEBUG, "unsupported protocol family %u\n", af);
293 m_freem(m);
294 IPSEC_ISTAT(sproto, ESP_STAT_NOPF, AH_STAT_NOPF,
295 IPCOMP_STAT_NOPF);
296 return EPFNOSUPPORT;
297 }
298
299 /* NB: only pass dst since key_lookup_sa follows RFC2401 */
300 sav = KEY_LOOKUP_SA(&dst_address, sproto, spi, sport, dport);
301 if (sav == NULL) {
302 static struct timeval lasttime = {0, 0};
303 static int curpps = 0;
304
305 if (!ipsec_debug && ppsratecheck(&lasttime, &curpps, 1)) {
306 if (sport || dport) {
307 log(LOG_INFO,
308 "no key association found for SA"
309 " %s[%u]-%s[%u]/SPI 0x%08lx\n",
310 ipsec_address(&src_address, buf, sizeof(buf)),
311 ntohs(sport),
312 ipsec_address(&dst_address, buf2, sizeof(buf2)),
313 ntohs(dport),
314 (u_long) ntohl(spi));
315 } else {
316 log(LOG_INFO,
317 "no key association found for"
318 " SA %s-%s/SPI 0x%08lx\n",
319 ipsec_address(&src_address, buf, sizeof(buf)),
320 ipsec_address(&src_address, buf2, sizeof(buf2)),
321 (u_long) ntohl(spi));
322 }
323 } else if (ipsec_debug) {
324 IPSECLOG(LOG_DEBUG,
325 "no key association found for SA "
326 "%s-%s/SPI 0x%08lx/PROTO %u/PORT %u-%u\n",
327 ipsec_address(&src_address, buf, sizeof(buf)),
328 ipsec_address(&dst_address, buf2, sizeof(buf2)),
329 (u_long) ntohl(spi), sproto, ntohs(dport), ntohs(sport));
330 }
331 IPSEC_ISTAT(sproto, ESP_STAT_NOTDB, AH_STAT_NOTDB,
332 IPCOMP_STAT_NOTDB);
333 m_freem(m);
334 return ENOENT;
335 }
336
337 KASSERT(sav->tdb_xform != NULL);
338
339 /*
340 * Call appropriate transform and return -- callback takes care of
341 * everything else.
342 */
343 error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff);
344 KEY_SA_UNREF(&sav);
345 return error;
346 }
347
348 #ifdef INET
349 /*
350 * Common input handler for IPv4 AH, ESP, and IPCOMP.
351 */
352 void
ipsec4_common_input(struct mbuf * m,int off,int proto)353 ipsec4_common_input(struct mbuf *m, int off, int proto)
354 {
355 (void)ipsec_common_input(m, off, offsetof(struct ip, ip_p),
356 AF_INET, proto);
357 }
358
359 /*
360 * IPsec input callback for INET protocols.
361 * This routine is called as the transform callback.
362 * Takes care of filtering and other sanity checks on
363 * the processed packet.
364 */
365 int
ipsec4_common_input_cb(struct mbuf * m,struct secasvar * sav,int skip,int protoff)366 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav,
367 int skip, int protoff)
368 {
369 int prot, af __diagused, sproto;
370 struct ip *ip;
371 struct secasindex *saidx;
372 int error;
373
374 if (__predict_false(m == NULL)) {
375 panic("%s: NULL mbuf", __func__);
376 }
377 if (__predict_false(skip < sizeof(struct ip))) {
378 panic("%s: short skip", __func__);
379 }
380
381 KASSERT(sav != NULL);
382 saidx = &sav->sah->saidx;
383 af = saidx->dst.sa.sa_family;
384 KASSERTMSG(af == AF_INET, "unexpected af %u", af);
385 sproto = saidx->proto;
386 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
387 sproto == IPPROTO_IPCOMP,
388 "unexpected security protocol %u", sproto);
389
390 /*
391 * Update the IPv4 header. The length of the packet may have changed,
392 * so fix it, and recompute the checksum.
393 */
394 if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) {
395 char buf[IPSEC_ADDRSTRLEN];
396 cantpull:
397 IPSECLOG(LOG_DEBUG,
398 "processing failed for SA %s/%08lx\n",
399 ipsec_address(&sav->sah->saidx.dst, buf,
400 sizeof(buf)), (u_long) ntohl(sav->spi));
401 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
402 IPCOMP_STAT_HDROPS);
403 error = ENOBUFS;
404 goto bad;
405 }
406 ip = mtod(m, struct ip *);
407 ip->ip_len = htons(m->m_pkthdr.len);
408 ip->ip_sum = 0;
409 ip->ip_sum = in_cksum(m, ip->ip_hl << 2);
410
411 /*
412 * Update TCP/UDP checksum
413 * XXX: should only do it in NAT-T case
414 * XXX: should do it incrementally, see FreeBSD code.
415 */
416 m = ipsec4_fixup_checksum(m);
417 if (m == NULL)
418 goto cantpull;
419 ip = mtod(m, struct ip *);
420
421 prot = ip->ip_p;
422
423 M_VERIFY_PACKET(m);
424
425 key_sa_recordxfer(sav, m);
426
427 if ((inetsw[ip_protox[prot]].pr_flags & PR_LASTHDR) != 0 &&
428 ipsec_in_reject(m, NULL)) {
429 error = EINVAL;
430 goto bad;
431 }
432
433 /*
434 * There is no struct ifnet for tunnel mode IP-IP tunnel connection,
435 * so we cannot write filtering rule to the inner packet.
436 */
437 if (saidx->mode == IPSEC_MODE_TUNNEL)
438 m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL;
439
440 (*inetsw[ip_protox[prot]].pr_input)(m, skip, prot);
441 return 0;
442
443 bad:
444 m_freem(m);
445 return error;
446 }
447 #endif /* INET */
448
449 #ifdef INET6
450 int
ipsec6_common_input(struct mbuf ** mp,int * offp,int proto)451 ipsec6_common_input(struct mbuf **mp, int *offp, int proto)
452 {
453 int l = 0;
454 int protoff, nxt;
455 struct ip6_ext ip6e;
456
457 if (*offp < sizeof(struct ip6_hdr)) {
458 IPSECLOG(LOG_DEBUG, "bad offset %u\n", *offp);
459 IPSEC_ISTAT(proto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
460 IPCOMP_STAT_HDROPS);
461 m_freem(*mp);
462 return IPPROTO_DONE;
463 } else if (*offp == sizeof(struct ip6_hdr)) {
464 protoff = offsetof(struct ip6_hdr, ip6_nxt);
465 } else {
466 /* Chase down the header chain... */
467 protoff = sizeof(struct ip6_hdr);
468 nxt = (mtod(*mp, struct ip6_hdr *))->ip6_nxt;
469
470 do {
471 protoff += l;
472 m_copydata(*mp, protoff, sizeof(ip6e), &ip6e);
473
474 if (nxt == IPPROTO_AH)
475 l = (ip6e.ip6e_len + 2) << 2;
476 else if (nxt == IPPROTO_FRAGMENT)
477 l = sizeof(struct ip6_frag);
478 else
479 l = (ip6e.ip6e_len + 1) << 3;
480 KASSERT(l > 0);
481
482 nxt = ip6e.ip6e_nxt;
483 } while (protoff + l < *offp);
484
485 /* Malformed packet check */
486 if (protoff + l != *offp) {
487 IPSECLOG(LOG_DEBUG, "bad packet header chain, "
488 "protoff %u, l %u, off %u\n", protoff, l, *offp);
489 IPSEC_ISTAT(proto, ESP_STAT_HDROPS,
490 AH_STAT_HDROPS,
491 IPCOMP_STAT_HDROPS);
492 m_freem(*mp);
493 *mp = NULL;
494 return IPPROTO_DONE;
495 }
496 protoff += offsetof(struct ip6_ext, ip6e_nxt);
497 }
498 (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto);
499 return IPPROTO_DONE;
500 }
501
502 /*
503 * IPsec input callback, called by the transform callback. Takes care of
504 * filtering and other sanity checks on the processed packet.
505 */
506 int
ipsec6_common_input_cb(struct mbuf * m,struct secasvar * sav,int skip,int protoff)507 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip,
508 int protoff)
509 {
510 int af __diagused, sproto;
511 struct ip6_hdr *ip6;
512 struct secasindex *saidx;
513 int nxt;
514 u_int8_t prot;
515 int error, nest;
516
517 if (__predict_false(m == NULL)) {
518 panic("%s: NULL mbuf", __func__);
519 }
520
521 KASSERT(sav != NULL);
522 saidx = &sav->sah->saidx;
523 af = saidx->dst.sa.sa_family;
524 KASSERTMSG(af == AF_INET6, "unexpected af %u", af);
525 sproto = saidx->proto;
526 KASSERTMSG(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
527 sproto == IPPROTO_IPCOMP,
528 "unexpected security protocol %u", sproto);
529
530 /* Fix IPv6 header */
531 if (m->m_len < sizeof(struct ip6_hdr) &&
532 (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
533 char buf[IPSEC_ADDRSTRLEN];
534 IPSECLOG(LOG_DEBUG, "processing failed for SA %s/%08lx\n",
535 ipsec_address(&sav->sah->saidx.dst,
536 buf, sizeof(buf)), (u_long) ntohl(sav->spi));
537 IPSEC_ISTAT(sproto, ESP_STAT_HDROPS, AH_STAT_HDROPS,
538 IPCOMP_STAT_HDROPS);
539 error = EACCES;
540 goto bad;
541 }
542
543 ip6 = mtod(m, struct ip6_hdr *);
544 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
545
546 m_copydata(m, protoff, sizeof(prot), &prot);
547
548 key_sa_recordxfer(sav, m);
549
550 /*
551 * See the end of ip6_input for this logic.
552 * IPPROTO_IPV[46] case will be processed just like other ones
553 */
554 nest = 0;
555 nxt = prot;
556 while (nxt != IPPROTO_DONE) {
557 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) {
558 IP6_STATINC(IP6_STAT_TOOMANYHDR);
559 error = EINVAL;
560 goto bad;
561 }
562
563 M_VERIFY_PACKET(m);
564
565 /*
566 * Protection against faulty packet - there should be
567 * more sanity checks in header chain processing.
568 */
569 if (m->m_pkthdr.len < skip) {
570 IP6_STATINC(IP6_STAT_TOOSHORT);
571 in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m),
572 ifs6_in_truncated);
573 error = EINVAL;
574 goto bad;
575 }
576
577 /*
578 * Enforce IPsec policy checking if we are seeing last header.
579 * Note that we do not visit this with protocols with pcb layer
580 * code - like udp/tcp/raw ip.
581 */
582 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
583 ipsec_in_reject(m, NULL)) {
584 error = EINVAL;
585 goto bad;
586 }
587
588 /*
589 * There is no struct ifnet for tunnel mode IP-IP tunnel connection,
590 * so we cannot write filtering rule to the inner packet.
591 */
592 if (saidx->mode == IPSEC_MODE_TUNNEL)
593 m->m_pkthdr.pkthdr_flags |= PKTHDR_FLAG_IPSEC_SKIP_PFIL;
594
595 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt);
596 }
597 return 0;
598
599 bad:
600 m_freem(m);
601 return error;
602 }
603 #endif /* INET6 */
604